RT Journal Article
SR Electronic
T1 Molecular transport and packing underlie increasing ribosome productivity in faster growing cells
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.10.27.466129
DO 10.1101/2021.10.27.466129
A1 Akshay J. Maheshwari
A1 Emma Gonzalez
A1 Alp M. Sunol
A1 Drew Endy
A1 Roseanna N. Zia
YR 2021
UL http://biorxiv.org/content/early/2021/10/28/2021.10.27.466129.abstract
AB Faster growing cells must make proteins more quickly. This occurs in part through increasing total ribosome abundance. However, the productivity of individual ribosomes also increases, almost doubling via an unknown mechanism. To investigate, we model both physical transport and chemical reactions among ensembles of individual molecules involved in translation elongation in Escherichia coli. We predict that the Damköhler number, the ratio of transport latency to reaction latency, for translation elongation is ~4; physical transport of individual ternary complexes accounts for ~80% of elongation latency. We also model how molecules pack closer together as growth quickens. Although denser cytoplasm both decreases transport distances and hinders motion, we predict that decreasing distance wins out, offering a simple mechanism for how individual elongating ribosomes become more productive as growth quickens. We also quantify how crowding imposes a physical limit on the performance of self-mixing molecular systems and likely undergirds cellular behavior more broadly.Competing Interest StatementThe authors have declared no competing interest.